I don't know if this helps, but I have Nerine undulata in full glory now and it's the latest of all nerine I grow. I grow N.undulata in two different ways. One group in morning sun with occasional waterings in summer and they are virtually evergreen. Another group is in full sun, without any watering at all, left to the elements. These plants suffered quite a lot in the first years, but now they have adjusted to a winter rainfall schedule, loosing the leaves in summer. These come up again with the first rains and are in blooming now. They can't compare with those in partial shade, they are a bit stressed but are healthy plants anyway, just smaller. Angelo Porcelli south of Italy